Quote:
Originally Posted by alpal
TV digital signals have data correction but still I find if I flick a light switch or an air con switches off I get a glitch on the picture.
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TV digital systems are broadcast. It's not a peer-to-peer file transfer and it's not designed to avoid the occasional drop out.
Quote:
Originally Posted by alpal
Yes - there are error checks & re-transmission but if the interference is bad then it can't give perfect files - no matter how many times it tries to re-transmit - there are still errors.
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The data is in small packets and these are retransmitted when an error occurs, not the whole file. It *is* possible to have reliable file transfer in the presence of even high error rates.
Quote:
Originally Posted by alpal
If I'm wrong then explain why I've seen NC milling machines in factories controlled by optic fiber cables from an office 100 meters away?
Why don't they run them on WIFI?
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I don't know for sure but here are some possible reasons:
- they are designed to operate in very hostile environments (welding, etc.)
- they are concerned about interfering with other analog devices (WiFi uses shared spectrum)
- timing is critical and retransmit delay is a potential problem
- they were designed that way back when WiFi technology was less mature and there's no cost pressure to change
- they are over engineering and butt covering in case of lawsuits